MultiCoreLib

changes since last public version:
- added ItemManagementTool
- added RegistrationTool

Item Management Tool:

- getCountOfItemInInventory(PlayerInventory inv, Item itemToCount): Takes in an inventory to search in, and an item to count. returns the the amount of the matching items (int). can be larger than 64 since it counts all matching items.

Registration Tool:

- registerNoItem(String name, Supplier<T> block, DeferredRegister<Block> BLOCKS_): Useful for quickly registering a block without its item form. Takes in a string as an id, a block class supplier,  and the block registry object to register the block into.

- registerWithItem(String name, Supplier<T> block, Item.Properties itemProperties, DeferredRegister<Block> BLOCKS_, DeferredRegister<Item> ITEMS_): Useful for quickly registering blocks including their item forms. Takes in a string as an id, a block class supplier,  Item.Properties to set the properties of the item form, the block registry object to register the block into, and the item registry object to register the block into.

- buildEntity(EntityType.IFactory<T> entity, Class<T> entityClass, float width, float height, EntityClassification classification, int trackingRange, int updateinterval, DeferredRegister<EntityType<?>> ENTITIES_): Useful for registering and building entities easily.